A common method for passively detecting gas leaks in systems utilizing a pressurized gas is to include an odorant in the gas such that, if gas leaks from the system, the odor of the gas in the area surrounding the system will alert individuals in the vicinity of the system that a gas leak is occurred. An example of this is the odorant added to natural gas. However, a gas odorant cannot be used in conjunction with systems utilizing pressurized hydrogen gas, such as hydrogen fuel cell vehicles, due to the small size of H2 gas molecules relative to the odorant molecules. More specifically, a leak in the system may allow the hydrogen gas to escape but not the odorant. Under such conditions, a hydrogen gas leak from the system may go undetected.
Many systems which utilize pressurized hydrogen gas utilize active detection systems in order to detect the presence of a hydrogen gas leak. For example, hydrogen fuel cell vehicles may contain a variety of redundant systems for actively detecting a hydrogen gas leak from the system. These redundant systems may include pressure sensors to detect a pressure drop in the hydrogen gas storage tank and/or fuel lines connected to the hydrogen gas storage tank; flow rate meters to monitor the flow of hydrogen gas from the tank; and/or combustible gas sensors for detecting the presence of hydrogen gas outside of the storage tank and/or fuel lines. However, all of these various active detection systems require power from the hydrogen fuel cell vehicle to operate and as such, when the vehicle is switched off, the active detection systems deplete the battery system of the vehicle. Accordingly, the active detection systems may not work when the vehicle is off and may not be able to provide an operator of the vehicle with an indication that a hydrogen leak has occurred prior to the operator entering the vehicle and powering on the vehicle.
Accordingly, a need exists for alternative devices for detecting hydrogen gas leaks for use in conjunction with systems utilizing pressurized hydrogen gas.